1. Field of the Invention
The present invention relates to multihull boats, and more particularly to multihull boats with an extendable platform.
2. Related Art
There have been many alternative designs that seek to increase the deck space for watercraft on pontoons, including laterally extending decks and longitudinally extending decks. When extending the deck space longitudinally using a ramp, many prior art ramps do not provide any buoyancy to the section of the ramp being extended and others may have negligible buoyancy and slope downward and dip to near water level or at the water level, allowing sections of the deck to be splashed and get wet. Further, such ramps are unstable, particularly in rough weather or choppy water.
The present invention provides an increase in deck space by extending a lower deck longitudinally, while also providing additional longitudinal buoyancy that maintains the elevation of the lower deck above the surface of the water in a near parallel arrangement to the main deck and avoiding the sloping of the lower deck to water level. The increased buoyancy for the lower deck compensates for the increased structure being supported, which stabilizes the lower deck, even in rough waters. The extended space does not slope toward the water, providing a stable, safe surface to sit, walk or stand.
There are a number of different designs for boats with longitudinally extending decks. As an example of a longitudinally extending deck with a flotation device, U.S. Pat. No. 6,868,799 discloses an extendable ramp with a small cylindrical float located at the end of the ramp. The ramp slopes toward the water and the end of the ramp is essentially level with the water. This patent clearly teaches away from the present invention that provides longitudinal buoyancy to lift the deck and provide stability. As an example of a longitudinally extending deck without any flotation device, U.S. Pat. No. 8,056,496 discloses an extendable deck for a pontoon boat that is stowed under the main deck. The extendable deck has no flotation devices attached, but is levered from the bow of the boat. As the deck is extended beyond its half retracted position, the end of the floating deck begins sloping down and the deck designed to require support by a beach or a boat dock when it is fully extended. This patent likewise teaches away from the claimed invention having longitudinal buoyancy and its resulting stability and safety.
None of the prior art references discloses a secondary deck that is buoyantly supported by pontoons or any other flotation device when the secondary deck is stowed beneath the main deck to which the secondary deck is slidably connected. In addition to providing extra deck space, a secondary deck that has its own buoyant support that is operative when the deck is stowed and when the deck is extended can provide increased stability to the watercraft while maintaining the loading capacity of the watercraft. Known watercraft that merely add slidable planks, ramps or decks which do not offset the weight of these features with an increase in the buoyancy of the watercraft necessarily increase the total weight and therefore reduce the loading capacity of the watercraft. When a float on a ramp is only operable when the ramp is deployed, there is no increase in the buoyancy of the watercraft when the ramp is stowed and this can reduce the stability of the watercraft if the ramp is added to an existing watercraft design. Even if the abeam pontoons are sized larger to accommodate the addition of a ramp, the extension of a ramp that is not supported while it is stowed will necessarily produce a cantilevering effect that will increase the stress on the main deck structure and will also change the boat's attitude in the water while the ramp is cantilevered.